Theoretical and experimental studies on vibration control of sag cables in cable-stayed bridge by Oil Damper

摘要

Inclined sag cables in long span calble-stayed bridges are susceptible to large vibration due to wind excitation, wind-rain excitation or parametric excitation. Large cable vibration can easily lead to cable fatigue damage, wear out the corrosion protection tube, and eventually affect the safety of the whole bridge. To this connection, theoretical and experimental studies on vibration control of inclined sag cables using oil dampers are carried out in the Hong Kong Polytechnic University. A hybrid method is first developed for estimating modal damping ratios in a sag cable attributed to oil dampers installed. Effects of cable sag, cable inclination, damper stiffness, and damper direction on damper performance are investigated.k Theoretical studies are then extended to nonlinear behavior of the cable-damper system with large vibration amplitude. Experiments of free and forced vibrations of inclined sag cables with and without oil dampers are finally conducted to enhance the understanding of the problem and verify the theoretical solutions.